1. Field of Invention
This invention relates generally to a simple method for producing water-insoluble polysaccharides, and in particular, to the water-insoluble bio-compatible gels, films, porosity, sheets, fibers and spheres of this invention may be applied to various medical and cosmetic uses.
2. Description of the Related Art
Hyaluronic acid (“HA”) is a naturally occur muco-polysaccharide found for example, in synovial fluid, in vitreous humor, in capsules of some bacteria, in blood vessel and umbilical cord, and in other connective tissues. The polysaccharide consists of alternating N-acetyl-D-glucosamine and D-glucuronic acid residues joined by alternating beta. 1-3 glucuronic and beta. 1-4 glucosaminidic bonds, so that the repeating unit is-(1. fwdarw. 4)-. beta. -D-GlcA-(1. fwdarw. 3)-. beta. -D-GlcNAc-. In water, hyaluronic acid dissolves to form a highly viscous fluid. The molecular weight of hyaluronic acid isolated from natural sources generally falls within the range of several thousands to several millions daltons.
HA has been recently applied in the highly molecular of medicine. Generally, it has been reported that HA has functions of (1) naturally occurring in body, (2) no immunoreaction (3) degradation and adsorption by human body, (4) mass production and others.
HA, in chemically modified (“derivative”) form, is useful as a surgical aid, to prevent adhesions of body tissues during the post-operation period.
The derivative HA gel or film is injected into locus between the tissues that are to be kept separate to inhibit their mutual adhesion. To be effective the gel must remain in place and prevent tissue contact for a long enough time so that when the gel finally disperses and the tissues do
Chemically modified HA can also be useful for controlled release drug delivery, wound heading, anti-adhesion and comestibles.
Tomihata et al., 1997, Biomaterials, Vol.18, page 189-195, describles the preparation of cross-linked hyaluronic acid films of low water content by using the sodium salt of HA (with an average molecular weight of 1.5×106) and poly (ethylene glycol) diglycycidyl ether (EX-810) that as a cross-linker of HA.
They studied the effect of HA films cross-linked with EX-810 at different pH. The HA powder was dissolved in double distilled water of the pH of the HA solution by addition of 0.1N HCl and 0.1N NaOH, EX-810 was added to the solution and mixed under stirring at room temperature. The resulting solution was cast into a petri dish and allowed to dry under atmospheric pressure at 25° C. for 5 days to yield cross-linked HA film of 20 um thickness. Experimental results showed that the optimal pH of the cross-linking solution was at pH 6.1.
Malson, 1990, U.S. Pat. No. 4,963,666, states a process for producing the carboxyl-containing polysaceharides. A polysaceharide containing carboxyl group is reacted with a bi or poly-functional epoxide in an alkaline reagent. The cross-linking is performed during drying. Malson described the 200 mg of sodium hyaluronate MW 3×106 were mixed with 6 ml of 0.5% NaOH in a plastic tube and stirred with a glass rod until a clear homogeneous solution has been obtained. Then 2 ml of 1,4-butanediol diglycidyl ether (BDDE) were added and mixed thoroughly. The solution was subjected to shaking overnight and dialyzed against running distilled water for 24 hrs had a weakly acidic pH of about 5.5. The solution was poured into a petri dish of polystyrene and dried at room temperature for 2 days. A transparent, planar, water-insoluble film of 50 μm thickness was obtained.
Sakurai et al., 1987, U.S. Pat. No. 4,716,224, states a cross-linked hyaluronic acid and its use. In the invention, a poly-functional epoxy compound is selected from the group consisting of halomethyloxirane compounds and a bis-epoxy compound selected from the group consisting of 1,2-bis (2,3-epoxypropoxy) ethane, 1,4-bis (2,3-epoxypropoxy) butane, 1,6-bis (2,3-epoxypropoxy) hexane and a diglycidyl ether of biophenol A or bisphenol F, which has a crosslinking index of 5 to 20 per 100 repeating disaccharides composed of glucoronic acid and N-acetylglucosamine in hyaluronic acid, said cross-linked hyaluronic acid or pharmaccutically acceptable salt thereof being water soluble and stringy.
10 g of HA solution salt (a molecular weight, 7.3×105) were dissolved in 450 ml of 0.2N sodium hydroxide solution with cooling and the resulting solution was filtered with a 0.45 μm micro-filter. The filtrate was added to 40 ml of 10N sodium hydroxide solution and then 500 ml of ethanol and 6.0 ml of epichorohydrin with stirring. The reaction was effected at 20° C. for 24 hrs and then the reaction mixture was adjusted to pH 6.4 with acetic acid. By addition of 500 ml of ethanol, there was separated a white precipitate, which was then recovered by filtration, washed well with ethanol and dried under reduced pressure. In the other example, 2.0 g of HA sodium salt (a molecular weight, 2.0×106) were dissolved in 100 ml of 0.1N sodium hydroxide under cooling and 100 ml of dioxane and 4.3 g of 1,4-bis (2,3-epoxypropoxy) butane were added. Reaction was effected at 40° C. for 2 hrs. The reaction mixture were added to 200 ml of water, the resultant mixture was neutralized with 1N hydrochloric acid and then centrifuged at 300 rpm. The precipitate was washed well with a 1.0M aqueous solution of sodium chloride, and a 0.15M aqueous solution of chloride, dehydrated with ethanol and then dried. Finally, 1.7 g of the cross-linked HA was formed.
Burns et al., 1991, U.S. Pat. No. 5, 017,229, States a method for producing water insoluble derivatives of hyaluronic acid. They announced a water insoluble hyaluronic acid was abstained by using the solid content 0.4%-2.6% of hyaluronic acid and an activating agent. In the claims of this invention, the poly-anionic polysaccharides included hyaluronic acid, carboxyl methylcellulose, carboxymethylamylose, chondroitin-6-sulfate, dermatin sulfate, heparin and heparin sulfate. As the example of this invention described, sodium hyaluronate (400 mg; 1.0 mmole of carboxyl groups) having a molecular weight between 1×106-2×106 was dissolved in 10 ml of distilled water. The pH of the aqueous solution was adjusted to pH 4.75 by addition of 0.1N HCl. Then 314 mg of (1-ethyl-3-C3 -dimethylaminopropyl) carbodimide hydrochloride (EDC) was added in the HA solution. The reaction mixture was kept at room temperature for 5 hrs, after which time it had formed a thick insoluble hydroxyl gel.
Burns et al., 1996, U.S. Pat. No. 5,527,893, States a method for producing water insoluble derivatives of poly-anionic polysaccharides. As the example of the invention described, sodium hyaluronate (400 mg) was dissolved in 10 ml of distilled water. The pH of the aqueous solution was adjusted to pH 4.75 by addition of 0.1N HCl. Then 314 mg of EDC was added all at once followed by 190 mg of L-leucine methyl ether hydrochloride. The reaction mixture was kept at room temperature for 5 hrs, after which time it had formed the invention also features a method for preparing a water insoluble HA composition comprising an acyl derivative of a poly-anionic polysaccharide.
Kuo et al., 1994, U.S. Pat. No. 5,356,883, describes a method for preparing water-insoluble bio-compatible gels, films and sponges by reacting hyaluronic acid with a carbodiimide. As the example of the invention described, a solution of HA (5.5 mg) was brought to pH 4.75 using 0.1N HCl. The, a solution of EDC (1.67 mg) was added to the HA solution. The reagents were mixed for 2 hrs at room temperature. Ethanol equal to three volumes of the reaction mixture was added to precipitate the chemically modified HA. The precipitate was separate from the solution, washed, and dried. A viscous and homogeneous solution was formed when water was added to the precipitate.
Kuo et al., 1996, U.S. Pat. No. 5,502,081, States a substance having pharmaceutical activity covalent bonded to the modified hyaluronic acid that reacted with a monocarbodiimide.
Kuo et al., 2000, U.S. Pat. No. 6,013,679, States a method for preparing water-insoluble derivatives of hyaluronic acid by reacting hyaluronic acid with a carbodiimide.
De Belder et al., PCT publication No. WO 86/00912, describes a slowly-degradable gel, for preventing tissue adhesions following surgery, prepared by cross-linking a carboxyl-containing polysaccharide with a bi-or poly-functional epoxide. The gel has an infrared absorption frequency of carboxyl group (——COOH) of ester functional group at 1745 cm−1.400 mg of sodium hyaluronate molecular weight 3×106 was dissolved in 4 ml of distilled water for 2 hrs. Then 600 mg of 1,4-butanediol diglycidyl ether (BDDE) was added and admixed thoroughly. HA gel was formed after the 0.15 ml of glacial acetic acid was added and reacted at 60-70° C. for 15 hrs.
T. Malson et al., 1986, PCTP publication No. WO 86/00079, states a method for preparing viscous fluid containing a sterile and pyrogen-free gel of cross-linked hyaluronic acid by reacting hyaluronic acid with the poly-functional epoxide, halohydrin, epihalohydrin or halide.
T. Malson et al., 1990, PCT publication No. WO 90/09401, States a method for preparing a cross-linked hyaluronic acid with the phosphorous-containing reagent as a cross-linker.
T. Malson et al., 1998, U.S. Pat. No. 5,783,691, describes a cross-linked hyaluronic acid derivative in which the cross-linking has been achieved by means of reaction with a phosphorous-containing reagent, especially a derivative of an acid of phosphorus (V).
T. Malson et al., 1987, U.S. Pat. No. 4,716,154, States a method for preparing a vitreous humor substitute intended for ophthalmological uses and consisting of a gel of cross-linked hyaluronic acid. The major characteristic of the invention was that used the poly-functional epoxide, halohydrin, epihalohydrin or halide as a cross-linker of hyaluronic acid. As the example of invention described.
Only the dry solid content of HA solution was over 13.3% and cross-linked temperature was over 50° C., the cross-linked hyaluronic acid gels could be formed in a plastic tube.
Nobuhiko et al., 1993, Journal of Controlled Release, Vol 25, page 133-143, describes a method for preparing lipid microspheres-containing hyaluronic acid gels. The 20% dry solids content of the hyaluronic acid was dissolved in 1N NaOH solution. Then, the cross-linked HA gel was formed after the PGPGE (Polyglycerol Polyglycidyl Ether) epoxide that contained one molar ratio of repeating unit was added in the HA solution and mixed under stirring at 60° C. for 15 min.
Nobuhiko et al., 1992, Journal of Controlled Release, Vol 22, page 105-106, describes a method for preparing cross-linked hyaluronic acid gels. The 20% dry solid content of the hyaluronic acid was dissolved in 1N NaOH solution. Then, the cross-linked hyaluronic acid gel was formed after the EGDGE (Ethylene Glycol Diglycidyl Ether) or PGPGE that dissolved in the alcohol solution was added in the HA solution and mixed under stirring at 60° C. for 15 min.
Balazs et al., 1986, U.S. Pat. No. 4,582,865, states a method for preparing cross-linked gels of hyaluronic acid and products containing such gels. The major characteristic of the invention was that a mixture of sodium hyaluronate and other hydrophilic polymer in a dilute aqueous alkaline solution at a pH of not less than about 9 was cross-linked with divinly sulfone at about 20° C.
Hamilton et al., 1990, U.S. Pat. No. 4,937,279, states a method for preparating water insoluble derivatives of hyaluronic acid with EDG and L-leucine metyhy ester chloride.
Miller et al., 1998, U.S. Pat. No. 5,760,200, states a method for preparation water insoluble derivatived of poly-anionic polysaccharides. The cross-linking reaction of hyaluronic acid, EDC and L-leucine methyl ester chloride was carried out in an acidic solution.
Alginate is a polysaccharide gel that extracted from the sargassum. The alginate polysaccharide consists of 1,4-linked β-D-mannuronic acid (M) and 1,4-linked α-L-guluronic acid (G).
Thompson et al., 1996, U.S. Pat. No. 5,563,186, states a method for preparing cross-linked alginate-based gels for matrix conformance. A composition of matter for matrix conformance formed from an aqueous solution of an alginate polysaccharide and a method of forming an alginate polysaccharide gel are disclosed. A Group hA cation, a dialdehyde, or a diamine may be used to cross-link the resulting alginate gel.
Desai et al., 1994, U.S. Pat. No. 5,334,640, states a method for preparing ionic covalent cross-linked and cross-linking bio-compatible encapsulation compositions and methods. PEG diacrylate (PEG-DA) was added to a solution of sodium alginate, and then a photocross-linked alginate was formed while this solution was exposed to visible radiation or UV light radiation.
Patrick et al., 1998, U.S. Pat. No. 5,705,270, states a method for preparing micro-capsules prepared from cross-linking polysaccharides. One example of the invention was described as following: Sodium alginate was dried in a vacuum oven. The dry powder was suspended in dichloromethane dried, a two fold excess of acryloyl chloride and triethyl amine was added to remove HCl upon formation. The reaction was carried in round bottomed flask under argon with constant reflux for 24 hours. The reaction mixture was filtered to remove the alginate acrylate, and then the substituted alginate was washed twice with ethanol and dried in a vacuum. The substituted alginate was formed a photocross-linked alginate micro-capsule by emulsification technique and UV light radiation.
Iguchi et al., 1998, U.S. Pat. No. 5,811,531, states a method for preparing absorbent with stability against salts and process for production thereof. 100 parts of xanthan gum was placed in mixer and stirred with 4 parts of the aqueous of the cross-linking agent obtained by adding of ethylene glycol diglycidyl ether to the methanol solution. The obtained mixture was heated at 140° C. for 20 minutes to form the absorbent. The absorbent was obtained using sodium alginate, pectin, and guar gum in the same procedure as above described. G. Hamdi et al., 1998, Journal of controlled release, Vol 55. page 193-201, states an original method for study in vitro the enzymatic degradation of cross-linked starch micro-spheres. The aqueous phase was prepared by dissolving soluble starch in a 2M sodium hydroxide solution under mechanical stirring. The aqueous phase was pre-emulsified in a cyclohexane-chloroform mixture (4:1, v/v) containing 0.5 %(v/v) of sorbitane monooleate. This emulsion was then added under mechanical agitation at 600 rpm. The reaction was maintained at 40° C. for 18 hours. Micro-spheres were then isolated by centrifugation and washed with cyclohexane, extensively with deionized water and finally with ethanol 95%(v/v).
Chitin is the most abundant organic matter is mainly found in the outer shell at crustacea, cartilage, exoskeleton of insect and all wall of fungi. Chitin is a naturally occurring linear high molecular polysaccharide compound of alternating disaccharide units of N-acetyl-D-glucosamine and glucosamine jointed by β-1,4 bond. Chitin consists of about 2000-3000 monomers, having a molecular weight of approximately two millions, depending on the conditions of making and sources.
Chitosan was obtained from the deacetylation by using the thermal alkaline. Chitin and chitosan are naturally high molecular compounds, with good bio-compatible, biodegradation and almost nontoxin (Dose of lethal, LD50=16 g/Kg). Besides the different applications on the food industries, the anti-microbial effect of chitosan can be also applied to the encapsulating and pharmaceutics.
The used chitosan is low impart to the environment has one or more other beneficial properties such as bio-compatible and biodegradation, which make them suitable for many applications, such as the encapsulating materials, agricultural use, biomedical materials and pharmaceutics for a wide variety of use.
Unger et al., 1996, U.S. Pat. No. 5,525,710, states a method for preparing highly porous chitosan bodies. Chitosan flakes were dissolved in a solution of dilute acetic acid, and the viscous solution was centrifuged to remove air bubbles. The gel was then made by contacting the viscous hydrocolloid with a solution of sodium hyroxide for 24 hours. The gel was then sliced and immersed into the toluene solution, and cross-linked with 2,4-TDI. The cross-linked product was then dried in a vacuum oven, and ground to a powder, which contained highly pore volume of the cross-linked chitosan.
Roy et al., 1998, U.S. Pat. No. 5,770,712, state a method for preparing cross-linked hydrogel beads from chitosan. An aqueous suspension of chitosan beads were immersed in the 100% absolute alcohol, then 1,4-butanediol diglycidyl ether was added in the solution and mixed under stirring for 24 hours at room temperature. The unreacted terminal epoxide was removed by alcohol solvent. Chitosan beads were spread in the water solution, and then the diethylamino (DEA) was added in the solution and mixed under stirring for 16 hours at room temperature.
Chondroitin sulfate was extracted from the cartilage of cattle and fish. Chondroitin sulfate is the component of connective tissue, and also named as glycosaminoglycan, or galactosamino glucuronoglycan sulfate which is one of the biggest structures molecular in the body. Chondroitin sulfate is a high molecular polysaccharide composed of N-acetyl-D-glucosamine and glucuronic acid. Chondroitin sulfate can adsorb the water and nutrient source, like as a buffer, that avoids the cartilage to destroy early.
Sakurai et al., 1989, U.S. Pat. No. 4, 863,907, states a method for preparing cross-linked glycosaminoglycans and their use. As the example of the invention described, to a mixture of a 12.5% solution of ChS——C sodium salt and a 0.75N aqueous solution of NaOH was added 1 volume of ethanol under stirring and the resultant sticky precipitate was separated and recovered. This sticky precipitaye was added to the epichiorohydrin, the resulting mixture was kneaded well and then it was allowed to stand at 20° C. for 24 hours. The ChS——C sodium salt was synthesized in the reaction.
Matsuda et al., 1995, U.S. Pat. No. 5, 462,976, states a method for preparing photocurable glycosaminoglycan derivatives, cross-linked glycosaminoglycans and method of production. Anhydrous pyridine was added to a solution of hyaluronic acid tri-n-butylamine salt in dimethylformamide (DMF), followed by addition of cinamoyl chloride with vigorous stirring at room temperature. Esterification was allowed to proceed at 75° C. for 2 hours, then ethanol saturated with sodium acetate was added to the reaction mixture, the resulting precipitate was collected and thoroughly washed with ethanol, then the film formed was exposed to irradiation of 270 nm wavelength. Thus was obtained a cross-linked hyaluronic acid film.